On 28 August 2014 15:30, Laszlo Ersek <[email protected]> wrote:
> So we got, in the NOR-mapped FD file:
>
> address 0:  jump instruction to 4K, otherwise a bunch of emptiness
>             (according to erase polarity!)

Ideally this should be a proper complete vector table with
handlers for all the exception vectors. In particular it is a
nice touch if exceptions for things like invalid accesses
and undefined instructions end up in some sort of panic-abort
function that dumps a diagnostic message to the UART.
This isn't necessary for proper operation but it's handy if
you're trying to debug either UEFI itself or early kernel startup.
As a minimum you want to have them go somewhere sensible
(like a jump-to-self instruction) so that we definitely don't just
try to reenter UEFI at its start point (an effect that is more
likely in 32-bit ARM where the all-zeroes instruction is a NOP).

Does UEFI install a proper vector table at some point in
bootup by writing to the vector base address register? If
not then providing a sensible initial set of vectors is even
more important.

thanks
-- PMM

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